1. Technical Field of the Invention
The present invention relates to a method and apparatus for supplying slivers to a roving frame. More particularly, it relates to a method and apparatus for continuously supplying slivers to a roving frame.
2. Description of the Related Art
Japanese Examined Patent Publication Showa 46 (1971)-6544, Japanese Examined Patent Publication Showa 41 (1966)-2739, and Japanese Examined Patent Publication Showa 42 (1962)-6015 disclose methods and apparatuses for exchanging almost exhausted sliver cans with corresponding full packaged sliver cans, after the end portion of a sliver contained in each almost exhausted sliver can is pieced with the free end of a sliver contained in the corresponding full packaged sliver can obtained from a prior process.
In the first-mentioned related art, a conveyer is arranged at a position right behind a roving frame along the longitudinal direction thereof, and a number of groups of sliver supply cans supplying slivers to the roving frame, which number is identical to the number of spindles of the roving frame, are arranged in an alignment perpendicular to the longitudinal direction of and right behind the conveyer, so that slivers supplied from these sliver supply cans of each group are introduced to corresponding draft mechanisms of the roving frame, which are adjacent to each other. The above-mentioned sliver supply cans is hereinafter simply referred to as a sliver can. The volume of sliver contained in the sliver cans of each group is preset in a "taper" arrangement; for example, if each group is composed of 3 sliver cans, the sliver cans positioned nearest to the conveyer contain almost one-third of the full packaged volume, the following sliver cans contain almost two-thirds of the full packaged volume, and the sliver cans positioned farthest from the conveyer contain almost full packaged volume. Therefore, during the operation of the roving frame, the sliver cans of each group nearest to the conveyer are always exhausted after a constant time has passed. Therefore, in the first related art, when the sliver cans positioned nearest to the conveyer become exhausted, in each group of sliver cans, the above-mentioned exhausted sliver cans are displaced from the conveyer and transported to a terminal position near a frame end of the roving frame, while still supplying a sliver to the corresponding draft part of the roving frame via the corresponding sliver guide roller. When the end of the sliver contained in these sliver cans is displaced upward, so that an end thereof appears, this end of the sliver is pieced with a free end of a sliver from the full packaged sliver cans which have been carried to a standby position close to the above-mentioned terminal position. After completion of the above-mentioned sliver piecing operation, the completely exhausted sliver cans are displaced to a position outside the sliver supply position at the roving frame, and the above-mentioned full packaged sliver cans, at which the sliver piecing operation is completed, are displaced to the normal sliver supplying position at the roving frame. The above-mentioned combined sliver cans exchange and sliver piecing operations are repeatedly carried out for all sliver cans from which slivers are supplied to the corresponding draft parts of the roving frame. This related art, however, does not make any particular disclosure of how to piece the two sliver ends.
In the second related art, a sliver from a full packaged sliver can is positioned above a sliver from a sliver can, which will soon be exhausted, during the displacement of the full packaged sliver cans, is gripped by a pair of rollers, and then a free end of the sliver delivered from the rollers is separated by sucking this portion by means of a suction means. On the other hand, a free end of a sliver from a sliver supplying can, which will soon be exhausted, is also separated from the upstream portion of the supplied sliver passing through another pair of feed rollers, just before this free end of the supplied sliver is introduced to the nip point of the feed rollers, so that the separated end of the sliver from the full packaged sliver cans is doubled over the separated free end of the supplied sliver just before being introduced to the feed rollers, by introducing the above-mentioned separated portion of the sliver from the full packaged sliver can downwardly to the position at which the sliver is fed to the feed rollers, so that a sliver end piecing operation can be carried out.
In the third related art, the arrangement of the sliver cans behind the roving frame is divided into a number of groups in such a way that, in each group of sliver cans, which are positioned in alignment with each other, along a direction perpendicular to the longitudinal direction of the roving frame, the volume of sliver contained in those sliver cans is preset in a "taper" arrangement, for example, in each group arrangement of four sliver cans, the volume of sliver contained in the first sliver cans positioned nearest to the roving frame is almost equal to the full packaged volume, the volume of the subsequent sliver cans is three-fourths of the full packaged volume, the volume of the third group of sliver cans is almost one-half of the full packaged volume, and the last group of sliver cans, positioned farthest from the roving frame, have a volume of almost one-fourth of the full packaged volume. When the last sliver cans are at an almost exhausted condition, the piecing operation of the sliver end from these sliver cans with the sliver end of the full packaged sliver cans already prepared is made by a manual operation, and thereafter, the full packaged sliver cans replacing the almost exhausted sliver cans are displaced to the position at which the above-mentioned first sliver cans were positioned, by displacing the remaining three sliver cans for a distance corresponding to a space for positioning one sliver cans in a direction far from the roving frame. During this operation, the exhausted sliver cans are returned to a prior process.
In the above-mentioned prior art, however, the following problems remain unsolved.
That is, in the above-mentioned first prior art, the above-mentioned exhausted sliver cans are displaced to the terminal position near a frame end of the roving frame, while still supplying a sliver to the corresponding part of the roving frame via the corresponding sliver guide roller, when the piecing operation of the sliver supplied from the above-mentioned sliver cans with a free end of a sliver from a full packaged sliver can is carried out. Accordingly, for example, if sliver cans positioned at an almost longitudinal central portion of the conveyer are subjected to the above-mentioned cans exchanging operation, the length of sliver between an almost exhausted sliver can displaced to the above-mentioned terminal position and the corresponding sliver guide roller becomes so long that treatment of this portion after completion of the above-mentioned sliver piecing operation is very complicated and not practical.
On the other hand, in the above-mentioned second prior art, since full packaged sliver cans are prepared at the respective standby positions adjacent to the respective sliver cans which require a can exchange operation, the above-mentioned problem related to the first prior art cannot be eliminated. That is, the sliver piecing operation must be carried out precisely with respect to time because, in each sliver piecing operation, a free end of a sliver from a full packaged sliver can must be combined with a free end of a sliver being supplied to the feed rollers at a position precisely upstream of the feed rollers. To carry out the above-mentioned sliver piecing operation in the order of arrangement of the sliver cans along the cans alignment which is parallel to the conveyer, it is essential to control the volume of slivers contained in the full packaged sliver cans very precisely, to carry out the operation effectively. However, such a precise volume control of the full packaged sliver cans is not practical. To solve this problem, a simultaneous exchange of almost exhausted sliver cans positioned along the conveyer with respect to full packaged sliver cans may be considered. Even if such a simultaneous exchange operation is applied, however, it is essential to create a condition such that the free end of slivers of the sliver cans are positioned at the respective positions for carrying out the above-mentioned sliver piecing operation, and therefore, the above-mentioned requirement for controlling the volume of slivers contained in the full packaged sliver cans can not be eliminated.
In the third prior art, the can exchanging operation is carried out automatically and the sliver piecing operation is carried out at a position apart from a position upstream of and adjacent to the feed rollers, and thus the very severe requirement regarding the timing, as in the above-mentioned second prior art, can be eliminated. Nevertheless, since the sliver piecing operation is manually carried out, a problem still remains in that a full automatic operation of exchanging sliver cans, which involves an automatic sliver piecing operation, is still not obtained.